For more than a year, hackers with ties to the Chinese military have been eavesdropping on U.S. Chamber of Commerce officials involved in Asia affairs, authorities say.

The hackers had access to everything in Chamber computers, including, potentially, the entire U.S. trade policy playbook.

"The Chinese have attacked every major U.S. company, every government agency, and NGO's. Their attacking the Chamber of Commerce is part of a pattern of their attacking everything in the US. If you're working on U.S.-China relations with an NGO, government agency, you can be sure the Chinese are reading your emails and on your computer," Richard Clarke, former White House counter-terrorism adviser, told ABC News.

At one point, the penetration into the Chamber of Commerce was so complete that a Chamber thermostat was communicating with a computer in China. Another time, chamber employees were surprised to see one of their printers printing in Chinese.

"I don't think the Chamber of Commerce has anything worth stealing, but it's part of a pattern of the Chinese stealing of everything they can, and that's worrying," Clarke said.

Sources tell ABC News that at any given moment that there are hundreds of cyber attacks targeting U.S. companies and government agencies.

In late 2009, sources say China-based hackers broke into Google's computers and looked at the email accounts of human rights activists. In the same operation, 29 other companies were hit, including Yahoo and Morgan Stanley.

The same year, a Chinese spy at Ford Motor Company downloaded thousands of files on hybrid engine design and gave them to the Chinese government, and a cyber attack traced to China allegedly stole design secrets to a U.S. stealth fighter jet.

Congressional leaders say China is engaged in economic espionage on a scale never seen before.

"You stack all of that up and I think there's a case to be made that this may be the greatest transfer of wealth through theft and piracy in the history of the world and we are on the losing end of it," said Sen. Sheldon Whitehouse of Rhode Island.

Overall, the U.S. is hemorrhaging economic espionage to the tune of $250 billion.

"This is a national, long-term strategic threat to the United States of America. This is an issue where a failure is not an option," said Robert Bryant at the National Counterintelligence Executive.